67) Explain Database Basics
Databases are managed by a relational database management system (RDBMS). An RDBMS supports a database language to create and delete databases and to manage and search data. The database language used in almost all DBMSs is SQL, a set of statements that define and manipulate data. After creating a database, the most common SQL statements used are INSERT, UPDATE, DELETE, and SELECT, which add, change, remove, and search data in a database, respectively.
68) what is Database?
A repository to store data.
69) What is Table?
The part of a database that stores the data. A table has columns or attributes, and the data stored in rows.
70) Define Attributes?
The columns in a table. All rows in table entities have the same attributes. For example, a customer table might have the attributes name, address, and city. Each attribute has a data type such as string, integer, or date.
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31) How are ENUMs and SETs represented internally?
As unique integers representing the powers of two, due to storage optimizations.
32) How do you start and stop MySQL on Windows?
net start MySQL, net stop MySQL
33) How do you start MySQL on Linux?
/etc/init.d/mysql start
34) Explain the difference between mysql and mysql interfaces in PHP?
mysqli is the object-oriented version of mysql library functions.
What’s the default port for MySQL Server?
3306
35) What does tee command do in MySQL?
tee followed by a filename turns on MySQL logging to a specified file. It can be stopped by command note.
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1) What’s MySQL ?
MySQL (pronounced “my ess cue el”) is an open source relational database management system (RDBMS) that uses Structured Query Language (SQL), the most popular language for adding, accessing, and processing data in a database. Because it is open source, anyone can download MySQL and tailor it to their needs in accordance with the general public license. MySQL is noted mainly for its speed, reliability, and flexibility. …
2) What is DDL, DML and DCL ?
If you look at the large variety of SQL commands, they can be divided into three large subgroups. Data Definition Language deals with database schemas and descriptions of how the data should reside in the database, therefore language statements like CREATE TABLE or ALTER TABLE belong to DDL. DML deals with data manipulation, and therefore includes most common SQL statements such SELECT, INSERT, etc. Data Control Language includes commands such as GRANT, and mostly concerns with rights, permissions and other controls of the database system.
3) How do you get the number of rows affected by query?
SELECT COUNT (user_id) FROM users would only return the number of user_id’s.
4) If the value in the column is repeatable, how do you find out the unique values?
Use DISTINCT in the query, such as SELECT DISTINCT user_firstname FROM users; You can also ask for a number of distinct values by saying SELECT COUNT (DISTINCT user_firstname) FROM users;
5) How do you return the a hundred books starting from 25th?
SELECT book_title FROM books LIMIT 25, 100. The first number in LIMIT is the offset, the second is the number.
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